Such an optical switch arrangement is already known in the art, e.g. from the article "Transparent routing; the enabling factor towards all-optical networking" written by A. Fioretti, F. Masetti, M. Sotom from Alcatel Alsthom Recherche France, published in the proceeding ECOC 1994. Florence, Italy September 1994. Therein, and more specifically in the paragraph about the functional description of main optical network elements on page 504 and FIG. 3 on page 509, a transparent optical crossconnect is described, which is similar to the above mentioned optical switch arrangement and which provides optical connections by exploiting both wavelength and space domain and reroutes a wide range of incoming optical signals from optical inputs to optical outputs.
Due to increased transmission capacity in optical networks the ability to recover quickly from failures becomes extremely important. A way to prevent failures is to use an optical protection mechanism which explicitly preserves a back-up path for each active path and selects this back-up path in a selector when failure occurs on the active path. However identical optical data travelling over physically diverse optical fiber routes from a source optical node to a destination optical node has different amounts of propagation delay and as a result arrives at a different time in the selector of the destination optical node. For applications providing optical hitless protection switching, i.e. switching between active paths with minimal information loss, identical optical signals coming over different optical paths should arrive at the same time at the selector. However an optical switch arrangement which routes the identical incoming optical signals to the according optical selector can not ensure provision of these optical signals at the same time to the optical selector.